DWQ-2024-005568

Page 1

TECHNICAL MEMORANDUM

PREPARED FOR: Jeff Hiatt – Wastewater Supervisor (Payson City)
Tyler Lowe – WWTP Operator (Payson City)

COPIES: Travis Jockumsen – City Engineer (Payson City)

PREPARED BY: Jason Broome (Forsgren Associates)

DATE: July 30, 2024

SUBJECT: Phosphorus Variance Annual Report for 2023

INTRODUCTION

This Technical Memorandum presents the 2023 annual report related to the effluent phosphorus
limit variance for the wastewater treatment plant (WWTP).

BACKGROUND

On October 10, 2018, Payson City was granted a variance from the technically based phosphorus
effluent limitation (TBPEL) rule. The variance includes an interim phosphorus limit of 4.6 mg/L.
The variance is applicable until January 1, 2027 (per the UPDES permit issued April 1, 2024), at
which time Payson City must comply with the technical based phosphorus limitation of 1.0
mg/L. Payson city must demonstrate due diligence to maintain this variance by working towards
achieving the final limitation.

This annual report fulfills a requirement of the variance. The variance states that “The Annual
Report will provide a summary of progress and milestones achieved in all study, funding,
planning, funding, design and construction projects during the previous reporting period
projected progress and milestones scheduled to be completed during the following reporting
period, and if the project(s) are on schedule. The Annual Report will also provide information on
effluent phosphorus concentrations to determine Payson's compliance.” Additionally, “The
Annual Report must specifically state the economic benefit per year Payson City will receive
from January 1 to December 31 of the coming year from this due diligence variance for not
treating total phosphorus to 1.0 mg/L.”

Payson WWTP Phosphorus Variance Annual Report
Page 2 Payson City
July 2024

CURRENT CONDITIONS

Payson has been sampling for both total phosphorus (TP) and ortho phosphorus (OP) in their
influent and their effluent since July 2015. Phosphorus data is summarized in Table 1.

Table 1
Phosphorus Data
Year
Annual
Average
Effluent
Flow
Total Phosphorus Orthophosphate
Influent
Annual
Average
Concentration
Effluent
Annual
Average
Concentration
Influent
Annual
Average
Concentration
Effluent
Annual
Average
Concentration
MGD mg/L mg/L mg/L mg/L
2016 1.54 5.00 4.95 3.01 4.04
2017 1.67 4.80 4.93 3.10 4.52
2018 1.87 5.14 5.09 3.57 4.85
2019 1.72 5.00 4.59 - - 4.06
2020 1.61 6.15 5.04 - - 4.68
2021 1.72 7.00 5.13 - - 4.93
2022 1.70 8.10 4.99 - - 4.25
2023 1.88 6.94 5.03 - - 4.57

Figure 1
Phosphorus Graph for 2023

Payson WWTP Phosphorus Variance Annual Report
Page 3 Payson City
July 2024

ACTIONS TAKEN TO DATE

Table 2 lists the actions taken to date towards compliance with the TBPEL.

Table 2
Summary of Actions Taken to Date
Date Description of Action
Previous Years
Aug-2014 Obtained funding from Water Quality Board for planning study
Dec-2014 Retained Aqua Engineering for planning study work
Mar-2017 Completed initial draft planning study
Dec-2018 Terminated all hauled wastes into the WWTP
Jan-2019 Retained Statepoint Engineering for chemical removal evaluation
Jul-2019 City council passed resolution in support of biological treatment for phosphorus removal
Oct-2019 Submitted draft planning study to DWQ for review
Feb-2020 Began exploring potential funding sources
Dec-2020 Applied for funding through Water Quality Board
Dec-2020 Began engineer selection process
Jan-2021 Selected engineer for design (Forsgren Associates)
Mar-2021 Awarded funding by Water Quality Board
Apr-2021 Completed draft update to planning study (for oxidation ditch alternative)
Aug-2021 Received variance extension approval from DWQ
Aug-2021 Selected CMGC contractor (Alder Construction)
Oct-2021 Issued 10% design package for review
Dec-2021 Received 10% design construction cost estimate from Alder Construction
Mar-2022 Closed on DWQ funding package
Mar-2022 Issued equipment preselection packages
May-2022 Closed on early loan package in order to pre-purchase equipment
Jun-2022 Issued 30% design package for review
Aug-2022 Received 30% design construction cost estimate from Alder Construction
Aug-2022 Purchase used screw press for use as temporary backup dewatering
Sep-2022 Issued electrical equipment and metal building pre-purchase packages
Nov-2022 Issued 60% design package for review
Dec-2022 Issued purchase orders for equipment (through contractor)
This Year
Jan-2023 Begin receiving submittal packages for major equipment
Mar-2023 Issued 90% design for early works packages for review and GMP preparation
Apr-2023 Issued 90% design for remaining packages for review and GMP preparation
Apr-2023 Submitted 90% design to DWQ for review
Aug-2023 Begin construction of early works project (packages 1-5)
Sep-2023 Submitted 100% design package for final approval by DWQ
Nov-2023 Issued 100% design for package 7 for GMP preparation

Payson WWTP Phosphorus Variance Annual Report
Page 4 Payson City
July 2024

ACTIONS PLANNED FOR COMING YEAR

Table 3 lists the actions planned to be taken in the coming year towards compliance with the
TBPEL.

Table 3
Summary of Actions Planned for Coming Year
Date Description of Action
Jan-2024 Begin receiving deliveries of major process equipment
Feb-2024 Receive construction permit from DWQ
Mar-2024 Begin construction on packages 6 and 7
Aug-2024 Complete construction of early works packages

ECONOMIC BENEFIT ANALYSIS

This section calculates the cost of phosphorus removal that would be required to meet the
TBPEL. Options for use of either alum or ferric are included.

Table 4
Calculation of Economic Benefit
Item Units Aluminum
Sulfate
Ferric
Chloride Notes
Flow Data
Projected Annual Avg Effluent Flow mgd 1.9 1.9 2023 average, rounded up
Phosphorus Data
Avg Annual Effluent Orthophosphate mg/L 4.6 4.6 2023 average
Target Effluent Orthophosphate mg/L 1.0 1.0 TBPEL limit
Orthophosphate Reduction mg/L 3.6 3.6
Orthophosphate Removal Rate 78% 78%
Chemical Use
Required Dose of Chemical mg/L 160 60 Based on 2019 jar testing
Chemical Annual Usage (Dry Basis) ton/yr 463 174 Dose x flow x 8.34 x 365 / 2000
Chemical Costs
Chemical Unit Cost $/dry ton $553 $1,105 From 6/2020 report, inflated by 30%
Annual Cost $/yr $255,644 $191,733